1. Field of the Invention
The invention relates to a method and an apparatus for reproducing and/or recording information to/from an information recording medium on which a plurality of tracks are spirally formed.
2. Related Background Art
Hitherto, a magnetic disk, an optical disk, or the like has been known as a disk-shaped information recording medium. Information tracks to record information are concentrically or spirally formed on such a disk-shaped recording medium. Those information tracks are divided into a plurality of sectors and information is recorded and/or reproduced on a sector unit basis. When the recording or reproduction of continuous sectors existing in a plurality of sectors is executed, in a case of concentrical information tracks, in order to record or reproduce a next track, it is necessary to move a recording or reproducing head to the next track. However, in a case of spiral tracks, the recording or reproduction can be continuously executed without moving the head. Therefore, spiral information tracks are frequently used in an optical disk which handles continuous data and the like.
In a case of recording or reproducing a data block consisting of a plurality of continuous sectors by using a recording medium having spiral information tracks, the head is certainly moved to the head of the data block and, after that, the recording or reproducing is executed so that processes can be successively performed. On the other hand, in a case of moving the head to the head of the data block, in order to move the head at a high speed, a coarse seeking is first performed at a high speed and a sector ID (identification data) is detected in this region. When there is an error, it is corrected and a minute seeking is executed, thereby accessing to a target sector. The above seeking operation will now be practically explained with reference to FIGS. 1 to 3. FIG. 1 is a diagram showing a part of the spiral information tracks on a recording medium. Tracks n-1, n, and n+1 are formed from the inner rim direction toward the outer rim direction. It is assumed that data is recorded or reproduced from the inner rim toward the outer rim. One track is divided into 25 sectors comprising sectors 0 to 22. One sector consists of 512 bytes.
FIG. 2 is a schematic diagram showing each track in FIG. 1. Sixteen sectors of the sectors 0 to 15 of the track n, that is, 8 kbytes are shown by a hatched portion and such a portion is referred to as a block A. A recording and reproducing process of the block A by the recording and/or reproducing apparatus will be described with reference to FIG. 3. First, to access the sector 0 of the track n corresponding to the position of the head of the block A, the coarse seeking is executed as shown by an arrow a. Subsequently, the sector ID is detected as shown by an arrow b. In this example, the track n and the sector 5 are detected. Therefore, the sector ID which has been detected because of the coarse seeking doesn't coincide with a target sector ID and a head goes beyond a target position. Therefore, in order to execute the minute seeking as mentioned above, the head is jumped to the track n-1 as shown by an arrow c and the apparatus waits for the rotation of the recording medium as shown by an arrow d. After that, the data block A is sequentially recorded or reproduced from the head sector as shown by an arrow e.
In the above conventional apparatus, however, in the case when the sector at which the head has arrived by the coarse seeking exceeds the target sector, even if the arrival position is located in the data block to be recorded or reproduced, the recording or reproduction is not performed and the minute seeking to the head sector is certainly executed. There is, consequently, a problem such that the whole seeking time increases.